Family History of Alcoholism May Raise Obesity Risk

People may substitute one addiction for another to satisfy brain's reward center, findings suggest

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Researchers at Washington University School of Medicine in St. Louis analyzed data from two large U.S. alcoholism surveys conducted in 1991-1992 and 2001-2002. According to the results of the more recent survey, women with a family history of alcoholism were 49 percent more likely to be obese than other women.

Men with a family history of alcoholism were also more likely to be obese, but this association was not as strong in men as in women, said first author Richard A. Grucza, an assistant professor of psychiatry.

One explanation for the increased risk of obesity among people with a family history of alcoholism could be that some people substitute one addiction for another. For example, after a person sees a close relative with a drinking problem, they may avoid alcohol but consume high-calorie foods that stimulate the same reward centers in the brain that react to alcohol, Grucza suggested.

In their analysis of the data from both surveys, the researchers found that the link between family history of alcoholism and obesity has grown stronger over time. This may be due to the increasing availability of foods that interact with the same brain areas as alcohol.

"Much of what we eat nowadays contains more calories than the food we ate in the 1970s and 1980s, but it also contains the sorts of calories -- particularly a combination of sugar, salt and fat -- that appeal to what are commonly called the reward centers in the brain," Grucza, explained in a university news release. "Alcohol and drugs affect those same parts of the brain, and our thinking was that because the same brain structures are being stimulated, overconsumption of those foods might be greater in people with a predisposition to addiction."

The study is published in the December issue of the journal Archives of General Psychiatry.

"In addiction research, we often look at what we call cross-heritability, which addresses the question of whether the predisposition to one condition also might contribute to other conditions," Grucza said. "For example, alcoholism and drug abuse are cross-heritable. This new study demonstrates a cross-heritability between alcoholism and obesity, but it also says -- and this is very important -- that some of the risks must be a function of the environment. The environment is what changed between the 1990s and the 2000s. It wasn't people's genes."

But, Grucza added, "Ironically, people with alcoholism tend not to be obese. They tend to be malnourished, or at least under-nourished because many replace their food intake with alcohol. One might think that the excess calories associated with alcohol consumption could, in theory, contribute to obesity, but that's not what we saw in these individuals."

More information

The U.S. National Institute on Alcohol Abuse and Alcoholism has more about family history.

SOURCE: Washington University School of Medicine in St. Louis, news release, Dec. 29, 2010